The invention relates to a method for SC-FDMA data transmission.
In mobile radio systems, particularly in transmissions in the uplink, that is to say from a mobile station to a fixed base station, are often limited by the power of the mobile station or of a corresponding terminal. Other limiting factors are temporal dispersion and interference. Portable devices are intended to have the lowest possible power consumption but at the same time to transmit data over distances of several kilometers. A power amplifier in portable devices of this kind is a problematic component in this regard, since the linearity of a power gain needs to cover both aspects, the gain dynamics of the channel and the power dynamics of modern radio-based transmission schemes, which are based on multicode or multicarrier transmission. A combination of their physical layer resources, that is to say codes or subcarriers, usually increases the power dynamics, even though the elemental waveforms have constant power, as is known by way of example from [1] J.-P. Javaudin, C. Dubuc, D. Lacroix, M. Earnshaw “An OFDM evolution for the UMTS high speed downlink packet access” in Proc. IEEE “http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber-9623” vol. 2, pp. 846-850, 2004.
For communication which is efficient in terms of power, minimum power dynamics are generally desirable. In this respect, the lead (back-off) can be reduced at the operating point of the amplifier and the efficiency of the amplifier can be improved, as is known from [2] J. Tubbax, B. Come, L. Van der Perre, L. Deneire, S. Donnay, M. Engels, “OFDM versus Single Carrier with Cyclic Prefix: A system-based comparison”, in Proc. IEEE “http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=7588”, vol. 2, pp. 1115-1119, 2001. The same amplifier allows the terminals to bridge a greater distance.
Single carrier transmission (SC transmission) is known to have lower power dynamics. For simple equalization of the transmission channel, these can be combined with a cyclic extension, as is known from [3] C. Desset, B. Côme, B. Debaillie, J. Driessche, J. Tubbax, W. Eberle, J. W. Weijers, “Constant Envelope Modulation Techniques for Non-linear Front-Ends,” available from: “http://www.imec.be/pacwoman/”, Deliverables/WP4/WP4.2-IMEC-4.2.1_constant_enveloppe_technique es-12-01-2004-V1.0.doc. and the references cited therein. More recent information theory, such as [4] A. Goldsmith, P. Varaiya, “Capacity of fading channels with channel side information” IEEE Trans. Inf. Theory, vol. 43, No. 6, November 1997, shows that the diversity in radio-based channels can be utilized by transmitting the signals in the spectral range with the best transmission quality.
To apply frequency domain resource splitting to multiple users (Frequency-Domain-Multi-User Scheduling), SC transmission is currently being developed further into a multiple access scheme which makes use of the advantages of both multipath and multisubscriber diversity. Consequently, SC-FDMA (single-carrier frequency-division multiple access) was proposed in [5] 3GPP TR 25.814 V7.0.0 (2006-06), available from: “http://www.3gpp.org”, for transmissions in the uplink in the long-term further development of cellular access networks (long term evolution) in the 3rd Generation Partnership Project (3GPP).
Virtual antenna designs are known generally from [8] D. Samardzija, P. Wolniansky, J. Ling, “Performance evaluation of the VBLAST algorithm in W-CDMA systems” in Proc. IEEE Vehicular Technology Conference, “http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=7588”, vol. 2, pp. 723-727, 2001, these subsequently being used as appropriate for the purpose of correct detection of the SC-FDMA signals.
An exemplary algorithm for implementing a discrete Fourier transformation using the “Mutual Prime Factor Cyclic Algorithm” (MPFCA) is known generally from [10] S. D. Morgera, “Efficient synthesis and implementation of large discrete Fourier transforms” SIAM Journal Comput., vol. 9, No. 2, pp. 251-272, 1980, for example.
Various aspects of data processing and transmission of data are known generally from [6] K. Gentile, “The care and feeding of digital, pulse-shaping filters”, available from: “http://www.rfdesign.com”; [7] H. G. Myung, J. Lim, D. J. Goodman “Peak-to-average power ratio of single carrier FDMA signals with pulse shaping” Proc. IEEE PIMRC 11-14 September 2006, Helsinki, Finland and [9] H. Chen, V. Jung-nickel, V. Pohl, C. von Helmolt, “A multicode space-frequency RAKE receiver,” in: Proc. 38th Asilomar Conference on “http://ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=9626”, vol. 1, page(s): 672-676, 2004.
Hence, SC-FDMA transmission using a DFT (Discrete Fourier Transformation) pre-coding unit and direct mapping of the result onto subcarriers of the subsequent IFFT (Inverse Fast Fourier Transformation) input signal is currently being contemplated. This provides advantages together with spectrally efficient modulation formats, but the pre-coding gain is reduced or even becomes negligible in conjunction with power-efficient modulation schemes.